(1) Field of the Invention
The present invention relates to a power distribution type antenna for radiating a number of beams consisting of an electromagnetic-wave, for instance, a microwave, which are formed by distributing high frequency electric power radiated from a primary projector. In particular, the invention relates to an antenna having a small and simple structure which is adapted for multipurpose and multifunction uses.
(2) Description of the Prior Art
Generally speaking, for the power distribution type antenna mentioned above, various kinds of antennas having different functions are employed for various purposes, such as a multibeam antenna having a primary projector supplied with electric power of a single frequency and antennas selected from a group consisting of a multi-frequency multibeam antenna, multi-polarized multibeam antenna, variable multibeam antenna and combinations thereof, in which group a primary projector is supplied with multi-frequency or multi-polarity electric power. Moreover, it is frequently required to provide such an antenna which additionally functions as a spot beam antenna or shaped beam antenna in which a primary projector is supplied with electric power having a single frequency, multi-frequency or multi-polarity.
The above mentioned conventional antennas of this kind have different structures adapted respectively for the above mentioned various purposes or functions, so that any one of those conventional antennas has no more than at most a few of these various functions. Accordingly, it is required even for use in a similar frequency range to newly design and to newly manufacture an antenna having a new structure which is quite different from those of conventional antennas according to its new purpose. As a result, complications are caused in manufacturing the newly designed antenna as well as in transporting and installing it since the skills involved in conveyance and installation are quite different from those for conventional antennas. Furthermore, most conventional antennas of this kind are relatively large, so that finding the space for their installation is a troublesome problem, particularly when they are mounted on a communication satellite.